First Australian record for Meiomeniidae!

After many hours of searching through the meiofauna, I found *one* specimen of an undescribed species of Meiomenia in a sand sample taken from east of Heron Island. Meiomeniids are tiny, interstitial solenogaster aplacophorans that feed on hydrozoans. They are known from Florida, the Caribbean, Bermuda, the Azores, Norway, Friday Harbor, and now Heron Island. I don't have facilities to take great pictures of meiofauna so instead I'll share Rick Hochberg's video of Meiomenia from Florida (they all look pretty similar anyway).

Otherwise, things are going well here on Heron. I'm fixing samples of Cryptoplax for various gene expression and other experiments and I'm still trying to spawn chitons with limited success... More on that soon.

Found heaps of Cryptoplax!

I was having trouble finding Cryptoplax on the north side of Heron Island. At Bernie's suggestion, I went for a reef walk at low tide on the southern side of the island and pretty easily found about 15 Cryptoplax on the underside of boulders. I brought the animals back to the lab and have since been trying to keep them from escaping from their aquarium.

Cryptoplax larvaeformis

Now I have both Cryptoplax and Acanthopleura and have been trying to convince them to spawn. They didn't cooperate on the full moon (even though it was Valentine's day!) and so far they haven't spawned tonight but I'm keeping a vigil. It's been suggested that thermal stress (both unusually cold and unusually warm) can induce spawning. If they don't spawn in the next couple of days, that'll be my next action.

Experimental aquaria for chiton spawning. If they start to
spawn, males will be isolated to avoid polyspermy and eggs

will be collected in 63 micron sieves, washed, and treated 

with appropriately diluted sperm.

Heron Island

G'day ya'll! I'm writing this post from beautiful Heron Island. I'm here collecting specimens for my postdoctoral research project in Bernie Degnan's Lab at The University of Queensland.

For this project, I'm examining the genes involved in the formation of the calcareous sclerites (sometimes called spicules) in chitons and aplacophorans. Heron is home to several species of chitons and aplacophorans have been seen here at least three times. So far it's been slow going... I've spent several days snorkeling on different parts of the island and seen lots of amazing stuff (beautiful corals, diverse fish, sharks, sea turtles, etc.) but I've only collected one specimen of the species of chiton I'm after: Cryptoplax larvaeformis. It seems that they like to hide during the day and mostly come out at night to feed. They are really good at hiding; I put the one I collected in a tank with a rock and it has completely disappeared (but I know it must be in there somewhere).

Tonight I'm going out for a night snorkel and hopefully it will be more productive!

New paper on the Schwabe organ in lepidopleuridan chitons

Last week a new study published by Sigwart et al. described a hitherto unreported structure in lepidopleuridan chitons called the Schwabe organ. Unlike chitonid chitons, the putatively plesiomorphic lepidopleuridan chitons lack an osphradium (sensory structure associated with the gills of Chitonids). However, in 2008 Enrico Schwabe observed "an elongated pair of patches of brown or purplish pigment stretching posterior from beneath the mouth lappets towards the start of the foot, and extending laterally on either side of the mouth" in Leptochiton algesirensis. The authors describe this structure in beautiful detail using light microscopy, 3D reconstruction, SEM, and TEM. Despite their thorough characterization, the exact function of this sensory structure remains unknown. They also review and compare the literature on chiton nervous systems and other known sensory structures.

Another interesting result of this study is the observation that at least the two species of Leptochiton examined both have a surprisingly large, well-developed brain. This is at odds with the traditional view that chitons have small, simple brains. More comparative studies are needed to determine if assumptions that chitons are "primitive" molluscs misled workers to presume they would have simple nervous systems and overlook this complexity or if there is a substantial difference between lepidopleuridan and chitonid chitons in terms of the size and complexity of the brain.

Leptochiton rugatus - my photo of a somewhat beat-up specimen
collected from Reid Rock near Friday Harbor Laboratories.